RF designs

[Travin77]

Well sorta. Here is what I am wondering. I have a car alarm. It is enabled and disabled by a rf keyfob which happens to operate at 303.875 mhz. In the keyfob, there is a pt-2240-d3 chip that sends an encoded signal via rf. Is there a way to copy-cat the signal with a pic and hardwire it directly to the antena wire of the alarm unit without going through a rf transmitter of the same frequency? Thanks

Travin

[blainecf]

Sorry, not that simple.

Among other things, these little buggers don't send the same signal every time - as a security precaution against exactly what you're talking about.

Anything you might want to hook up to an antenna has to be a transmitter, and it has to not only transmit on the same freq., but also using the same protocol.

Not to mention any legal infringements you might be causing because the mfr. intends their security system to be, well, secure.

[Travin77]

I know the keyfob is not a rolling code. It is fixed. I am just trying to find a way to hardwire to the alarm. I wanted to interface my carpc to the alarm. I really don't want to have to use a transmitter to do it. I had thought about putting an o-scope on the encoder chip in the keyfob and getting the waveform or what ever comes out of it and then tryng to duplicate that with a pic. Just curious of it is possible. Thanks

Travin

[Ioannis]

The only way to make receiver receive the signal is only through an transmitter. (how else could be?)

We as a company have produced for years such transmitters (with PIC inside of course!) that copy non-rolling codes. E-mail me private if interested in sending you a couple of them. They are not expensive and can be easily modified to be controlled by your external system.

Ioannis